Maddah (Persian: مداح), translates as eulogist or panegyrist; and it is attributed to religious singer. There is a kind of religious singer(s) in Islamic culture who are called Maddah that often participate in --anniversary-- funeral ceremonies of Muslims, particularly for the famous characters among the Islamic prophet Muhammad and twelve Imams of Shia; and they recite or sing in Islamic/sad manner for people (as a type of mourning).
The root of the word "Maddah" is "Madh" which means expressing the excellent traits of a character or a thing.
Maddah (or Dhakir) is an individual who mentions/praises the great characters and religious education in (religious) gatherings; and its performance ought to be mostly full of Eulogy/Marsiya; besides, Maddahi doesn't have special gender, age, group or elegy.
Idiomatically, Maddah means a dhakir or panegyrist who (often) stands beside the pulpit, and praises or turns into poetry about Ahlul-Bayt (and the Islamic prophet, Muhammad) and their tragedy, particularly regarding the disasters/tragedy of battle of Karbala, and Husayn ibn Ali's manner of martyrdom who was killed there with his companions by the enemies.